The invention is related to the field of fuel dispensers and, in particular, to a fuel dispenser having a nutating disk meter for metering the quantity of fuel dispensed by the fuel dispenser.
Fuel dispensers (often erroneously called xe2x80x9cfuel pumpsxe2x80x9d) at service stations dispense fuel from underground tanks to customer automobiles. In addition, the fuel dispensers measure the quantity of fuel dispensed so that customers may be billed for the amount of fuel that they receive.
The quantity of liquid fuel that is dispensed is measured using a fuel meter. Modern service stations often provide up to four different products or grades of fuel on each of two sides of a fuel dispenser. Each fuel dispenser therefore includes up to eight fuel meters, one for each grade of fuel on each side of the dispenser.
The type of fuel meter commonly used in fuel dispensers for the last fifty years is a positive displacement piston-type meter. This type of meter has traditionally been used due to its ability to measure liquid flow at both low rates of flow (i.e. xc2xd gallon per minute) and at high rates of flow (i.e. 15 gallons per minute). Typically, each piston-type meter has its own check valve and a pair of piston-type meters share a common filter manifold for connection of a fuel filter.
Piston-type meters are complicated because they have many moving parts. This results in considerable expense to manufacture and maintain fuel dispensers that use piston-type meters. Prior to shipment from the factory, piston-type meters are tested and calibrated for liquid metering accuracy. After testing, a metal tamper-proof seal is attached to the calibration wheel to insure that it is not readjusted in the field after installation by an unqualified or unauthorized person. Officials from state government departments, typically called the xe2x80x9cDepartment of Weights and Measures,xe2x80x9d periodically inspect fuel dispensers to determine their metering accuracy. These inspections are performed to insure that consumers receive the correct amount of fuel for which they have paid.
Over time and use, the internal components of a piston-type meter wear or become loose, and the level of metering accuracy drops. This progressive drop in metering accuracy is known in the industry as xe2x80x9cmeter drift.xe2x80x9d Meter drift may result in lost revenue due to an under-accounting of the quantity of dispensed fuel.
In very high volume fueling stations, it may be necessary for a certified service provider to recalibrate a piston-type meter several times a year. Many fuel dispensers will require replacement of their piston-type meters with either new or rebuilt piston-type meters over the life of the fuel dispenser. In order to repair or rebuild a conventional piston-type fuel meter it is necessary to remove the entire meter assembly from the dispenser. The plumbing lines and electrical communication lines must be disconnected to remove the piston-type meter assembly. This is a labor intensive and expensive process that causes significant down-time.
In addition, piston-type meters are large in size. A typical piston-type meter is about the size of a volley ball. A four-product dispenser with fueling on both sides would include eight positive displacement piston-type meters. To accommodate eight piston-type meters within the hydraulic cabinet of a fuel dispenser requires that the overall width of the dispenser be very large, typically over 48 inches wide. The large size of the hydraulic cabinet results in a correspondingly large fuel dispenser size, a heavy fuel dispenser, and high cost of manufacture and installation. Also, large fuel dispensers occupy a lot of space on a dispenser island at a service station and they obstruct the station attendant""s view of the fueling customer and vice versa.
There is a need for an improved fuel dispenser that is smaller than conventional fuel dispensers, accurate, and simple to install and maintain.
A fuel dispenser having a nutating disk meter for measuring the quantity of fuel dispensed and a housing. The housing includes a chamber within which the nutating disk meter is removably located.
The fuel dispenser receives fuel from a fuel source and dispenses the fuel to an output device. The fuel dispenser meters the quantity of fuel dispensed to the output device. The fuel dispenser includes a housing. An inlet port of the housing is coupled to the fuel source. An outlet port of the housing is coupled to the output device. A meter chamber in the housing has a chamber inlet, a chamber outlet, and a chamber opening. An inlet passage extends from the inlet port to the chamber inlet for conveying fuel received from the fuel source from the inlet port to the meter chamber. An outlet passage extends from the chamber outlet to the outlet port for conveying fuel from the meter chamber to the outlet port. A nutating disk meter disposed within the meter chamber of the housing is used for measuring the quantity of fuel that flows through the fuel dispenser. A chamber cover covers the opening of the meter chamber and seals the nutating disk meter in the meter chamber. The nutating disk meter includes a disk having a magnetic portion that rotates at a rate corresponding to the rate of fuel flow through the meter. A sensor disposed outside and adjacent to the meter chamber is magnetically coupled to the disk for detecting its rotation and generating a corresponding signal.